Engine valve for improved operating efficiency

ABSTRACT

An engine valve is provided with a valve head, a cap disposed opposite of the valve head; and a stem interposed between the valve head and the cap. The stem has a cylindrically shaped surface and at least one helical section embedded in the stem. The helical section includes alternating crests and roots in which the roots depend inwardly in a direction of a centerline of the valve such that the surface area of the stem is periodically interrupted by the helical section. The introduction of the valve with helical section in an engine increases engine efficiency and reduces fuel consumption. Methods of making and using the engine valve are also provided.

BACKGROUND OF THE DISCLOSURE

By improving operating efficiency of an internal combustion engine, fuel efficiency is also improved so that the engine requires less fuel over its operating life. To improve engine efficiency, lightweight materials can be used to manufacture component parts of an engine, including intake and exhaust valves. Even if no other engine component is modified, lightweight engine valves alone can increase engine performance and greatly reduce fuel consumption.

Lightweight engine valves are known that are constructed from ceramic materials, titanium aluminum alloys, as well as thermoplastics. Although material modifications may succeed in reducing the weight of an engine valve, some engine valves, such as those having ceramic valve heads, wear out more quickly from repetitive contact against respective valve seats. To increase valve service life, some composite engine valves employ metal alloy valve heads with valve stems of lightweight material. However, torque, tension, pressure and other forces may greatly wear on a joint between a metal valve head and its lightweight valve stem to limit the life of the composite engine valve prematurely.

What is needed in the engine industry is an intake and exhaust valve having the durability of conventional metal valves and the lightweight characteristics of composite material engine valves. The desired valves should be cost effective, relatively easy to manufacture, and interchangeable with existing engine valves.

BRIEF SUMMARY OF THE DISCLOSURE

The present disclosure is directed in general to a valve for improving efficiency in engines of various types, including but not limited to automobiles, trucks, farm equipment, motorcycles, boats, lawn and garden equipment, and the like. The engine valve broadly includes a solid valve stem having a helical groove inscribed into the stem or material ablated from the stem to form the helical groove. In operation, the helical groove reduces mass and frictional area of the valve to improve overall engine operating efficiency.

For example, in one embodiment according to the present disclosure, an engine valve may include a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem having a cylindrically shaped surface and a helical section, the helical section including a plurality of alternating crests and roots, the roots depending inwardly in a direction of a centerline of the engine valve such that the surface is periodically interrupted by the helical section.

A diameter of the stem of one such valve may be about 0.375 inches and one of the roots may have a depth, as measured from the surface, of about 0.075 inches to about 0.078 inches.

In this example, the helical section of the engine valve may be a one start section. The helical section may include from about six crests and six roots to about twelve crests and twelve roots. Alternatively, the engine valve may have a helical section having more than one start. The engine valve may also have more than one helical section, such as two helical sections that may be spaced apart from each other. A sealing element may be inserted between the two helical sections.

In another embodiment, an engine valve may include a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem including means for reducing engine valve contact area in an engine valve guide. The means for reducing engine valve contact area may be a helix inscribed in the stem. The helix may have more than one start.

In yet a further embodiment, an engine valve may include a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem having a helical groove adapted to move the engine valve from a first position to a second position under a reduced valve seat load to reduce a parasitic loss in engine function. In this example, the helical groove may have at least two crests and one root interposed between the two crests. Further, the helical groove may have more than one start.

According to another aspect of the disclosure, a poppet valve may be provided of a type that carries out the steps of receiving a load and moving from a first position to a second position in an engine, the poppet valve comprising means for improving heat exchange through a cylinder head in the engine and increasing torque and horsepower before valve float occurs, the means for improving including a helical ablation of the poppet valve. In this example, the poppet valve may include a stem, and the helical ablation may be applied to the stem to define a helix. Also, the means for improving heat exchange through a cylinder head in the engine and increasing torque and horsepower before valve float occurs may be a helix in a stem of the poppet valve.

In a further aspect, a method may be provided to reduce contact area of a valve in an engine to reduce valve seat load, to reduce valve spring load, to increase air-fuel mixture under a seat of the valve, and to reduce lifter and camshaft load. The method may include reducing a mass of a valve by forming a helical portion about a stem of the valve; installing the valve in a cylinder head of an engine; and increasing engine efficiency by reducing a coefficient of drag of the valve, wherein the helical portion is configured to have reduced surface contact in the engine. The helical portion according to this method may have one or more starts. Further, the mass removed in this exemplary method may be between about twenty percent to about twenty-five percent of a diameter of the stem.

Additional objects and advantages of the present subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features and elements hereof may be practiced in various embodiments and uses of the disclosure without departing from the spirit and scope of the subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like.

Methods of using the engine valve and its associated operation are also disclosed herein. It is to be understood that different embodiments, as well as different presently preferred embodiments, of the present subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures). Additional embodiments of the present subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objects above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a plan view of an engine valve according to one aspect of the disclosure, particularly showing a helical section formed in a stem of the valve;

FIG. 2 is a partial cutaway view of the engine valve as in FIG. 1, shown in an intended use environment; and

FIG. 3 is a plan view of another engine valve according to another aspect of the disclosure, particularly showing a variation of a helical section formed in a stem of the valve.

DETAILED DESCRIPTION OF THE DISCLOSURE

Detailed reference will now be made to the drawings in which examples embodying the present subject matter are shown. The detailed description uses numerical and letter designations to refer to features of the drawings. Like or similar designations of the drawings and description have been used to refer to like or similar parts of various exemplary embodiments.

The drawings and detailed description provide a full and written description of the present subject matter, and of the manner and process of making and using various exemplary embodiments, so as to enable one skilled in the pertinent art to make and use them, as well as the best mode of carrying out the exemplary embodiments. However, the examples set forth in the drawings and detailed description are provided by way of explanation only and are not meant as limitations of the disclosure. The present subject matter thus includes any modifications and variations of the following examples as come within the scope of the appended claims and their equivalents.

Turning now to FIG. 1, a valve for an engine is designated in general by the number 10. The exemplary valve 10 includes a cap or tip 12, a valve head 14, and a valve stem 16 having a centerline C/L therethrough. As shown, the cap 12, the valve head 14, and the valve stem 16 may be of unitary construction to avoid points of weakness, such as connecting joints between different materials. For instance, the valve stem 16 is shown tapering into a fillet portion or shoulder 18 leading into the valve head 14 with a combustion face or chamber portion 20 that faces a combustion chamber of an engine, as described below. Although the entire valve 10 or selected sections may be formed from ceramic materials, thermoplastics, titanium, aluminum, steel or other metals and alloys, or some combination of these materials, it has been discovered that a helical groove or portions thereof can be used to make the valve 10 lightweight to improve overall engine operating efficiency and fuel efficiency.

FIG. 1 shows that the valve stem 16 includes at least one helical groove or helix section 22. In this example, two helicals 22 are spaced apart by one or more landings or necks 24 that may help seal in oil or other lubricants and also help to increase structural integrity in some applications. In a particular embodiment, a sealing element such as an o-ring or band 36 may be provided for additional sealing functions.

In the example shown in FIG. 1, the helicals 22 may be made by turning the valve 10 on a cutting machine, by laser ablation, by acid or laser etching, or by inscribing the valve 10 to form the helicals 22, with or without the neck 24. Alternatively, the valve 10 can be molded to include the helicals 22 and/or the neck 24 pre-formed in the stem 16. Aside from its method of formation, the valve 10 possesses a tensile strength (T.S.) of about 3400 pounds. The T.S. of the valve 10 is therefore greater than three times (3×) the necessary strength for the valve 10 to withstand discrete maximum forces of about 1000 pounds at any time during engine operation, including spring loads of about 500 pounds.

FIG. 1 particularly shows that each helical 22 has a helical angle of about eleven degrees, fifty-eight minutes and fifty-one seconds (11° 58′ 51″) (θ) formed at a right hand angle with one start, as depicted by element number 34. To accommodate the helicals 22, the stem 16 has a cylindrically shaped surface 32 with a diameter of about 0.375 inches. As shown most clearly in an inset of FIG. 1, the helicals 22 each have a plurality of lands or crests 26 and complementary inner surfaces or roots 28. Although not depicted to scale, a pitch 30 is approximately 0.250 inches between crests 26 and each crest 26 is approximately 0.100 inches wide. A depth from each crest 26 to each root 28 is approximately 0.075 inches, but no deeper than about 0.078 inches as limited by the diameter of the valve 10 in this example. Also shown, a chamfer or radius transitioning each root 28 to each crest 26 is about 0.250 inches.

Although FIG. 1 shows the valve 10 with two helicals 22 located at specific areas on the stem 16, other valve sizes and orientations and shapes of the helicals 22 are contemplated by the disclosure to meet particular industry needs and requirements. For instance, only one helical 22 need be provided, or the helicals 22 as shown in FIG. 1 could be spaced further apart or closer together (thus, neck 24 could be made larger or smaller). Additionally, the helicals 22 may have configurations other than purely helical, such as helical spline, spline broach, etcetera, and the valve stems 16 may have profiles other than ≈12°, such as up to 130° for larger and longer valve stems. The helical 22 also need not be continuous. There may be intermittent helical portions spaced apart from each other in the helical sections 22. So, the disclosure and the appended claims contemplate changes in groove geometry based on different valve diameters and lengths. Further, changes in root depth, angles of helixes, intermittent or staggered helixes, and different positions along valve stems may be made to accommodate a variety of engine types. Thus, those skilled in the art will therefore appreciate that the specific valve 10 is not limited to the example shown in FIG. 1.

Turning to FIG. 2 the valve 10 is shown in an operational environment, such as an automobile engine 5. As shown, the valve 10 is installed in a cylinder head 7 with the valve stem 16 cradled in a valve guide 9 while the cap 12 extends from a valve spring 13. The valve head 14 is urged against a valve seat 11 by the valve spring 13. As briefly introduced, the engine 5 is intended to represent any engine that requires a lightweight durable valve such as the valve 10; therefore, the engine 5 could be from a boat, an airplane, a lawn mower or the like and is not limited to an automobile engine.

As shown by the double-headed arrows in FIG. 2, as the engine 5 operates, the valve spring 13 is compressed by a cam assembly to move the valve 10 up and down, respectively away from and toward a combustion chamber of the engine 5. The helical grooves 22, having reduced the mass of the valve 10, also reduce contact area in the valve guide 9, i.e., the valve stem 16 has less surface area sliding against the valve guide 9. More specifically, while the crests 26 contact or slide against the valve guide 9, the spaces that result from the presence of the roots 28 serve to reduce the overall surface area of the valve stem 16, thus reducing friction within the valve guide 9. This results in reduced parasitic loss in the valve train, improved heat exchange through the cylinder head 7, reduced load on the valve spring 13, reduced lifter and cam shaft load, reduced load on the valve seat 11, and an increased area for air-fuel mixture under the valve seat 11. Accordingly, the helical grooves 22 increase overall engine efficiency without sacrificing the durability and necessary strength of the valve 10.

As noted above, variations in groove geometries and profiles may be made to accommodate different types of valves and engines. For instance, as shown in FIG. 3, a valve 110 includes a “two start” helical groove 122. As shown, the groove 122 “starts twice” at area 134. This geometry results in about 180° between turns or starts and a helical angle of about twenty-two degrees, fifty-nine minutes and forty-nine seconds (22° 59′ 49″) (θ′). Thus, the helical angle θ′ may be suitable for larger and longer valve stems. Also in this example, one of the grooves 122 runs clockwise and the other of the grooves 122 runs counter-clockwise to improve with fluid sealing and structural strength in some applications.

Aside from the number of starts in FIG. 3, which may be more than two, the exemplary valve 110 also includes a cap or tip 112, a valve head 114, and a valve stem 116 defining a centerline C/L therethrough. The cap 112, the valve head 114, and the valve stem 116 may be unitarily constructed of the same material to avoid points of weakness suffered by connecting joints between different materials.

As further shown in FIG. 3, the valve stem 116 tapers into a shoulder or chamfered area 118 leading into valve head 114. The valve head 114 has a combustion face or chamber portion 120 that faces a combustion chamber of an engine, as described above. The valve stem 116 may include more than one helical grooves 122. The grooves 122 may be set apart by one or more necks 124 that may include a ring or band 136. Each of the grooves 122 may have a plurality of crests 126 and roots 128 similar to those described in other embodiments noted herein. Like grooves previously described, the helical grooves 122 and their respective plurality of crests 126 and roots 128 serve to reduce the mass of the valve 110 and its surface contact area. In other words, the crests 126 (and, if included, the neck 124) are the only point bearing surfaces of the valve 110 in contact with a valve guide of the engine (see, e.g., valve guide 9 of FIG. 2). It is well known that drag coefficient (C_(d)) is associated with a particular surface area, so an object having less surface area like the valve stem 116 will also have a lower drag coefficient (C_(d)) and have less drag. Therefore, the coefficient of drag (C_(d)) of the valve 110 is lower than that of conventional valves and increases overall engine operating and fuel efficiencies.

While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art. 

1. An engine valve, comprising: a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem having a cylindrically shaped surface and a helical section, the helical section including a plurality of alternating crests and roots, the roots depending inwardly in a direction of a centerline of the engine valve such that the surface is periodically interrupted by the helical section.
 2. The engine valve as in claim 1, wherein a diameter of the stem is about 0.375 inches and one of the roots has a depth, as measured from the surface, of about 0.075 inches to about 0.078 inches.
 3. The engine valve as in claim 1, wherein the helical section is a one start section.
 4. The engine valve as in claim 3, wherein the helical section includes from about six crests and six roots to about twelve crests and twelve roots.
 5. The engine valve as in claim 1, wherein the helical section has more than one start.
 6. The engine valve as in claim 1, further comprising at least one other helical section.
 7. The engine valve as in claim 6, wherein the two helical sections are spaced apart from each other.
 8. The engine valve as in claim 6, further comprising a sealing element disposed between the two helical sections.
 9. An engine valve, comprising: a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem including means for reducing engine valve contact area in an engine valve guide.
 10. The engine valve as in claim 9, wherein the means for reducing engine valve contact area is a helix inscribed in the stem.
 11. The engine valve as in claim 1, wherein the helix has more than one start.
 12. An engine valve, comprising: a valve head; a tip portion disposed opposite of the valve head; and a stem interposed between the valve head and the tip portion, the stem having a helical groove adapted to move the engine valve from a first position to a second position under a reduced valve seat load to reduce a parasitic loss in engine function.
 13. The engine valve as in claim 12, wherein the helical groove includes at least two crests and one root interposed between the two crests.
 14. The engine valve as in claim 12, wherein the helical groove has more than one start.
 15. A poppet valve of a type that carries out the steps of receiving a load and moving from a first position to a second position in an engine, the poppet valve comprising means for improving heat exchange through a cylinder head in the engine and increasing torque and horsepower before valve float occurs, the means for improving including a helical ablation of the poppet valve.
 16. The engine valve as in claim 15, wherein the poppet valve includes a stem, the helical ablation being of the stem and defining a helix.
 17. The engine valve as in claim 15, wherein the means for improving heat exchange through a cylinder head in the engine and increasing torque and horsepower before valve float occurs being a helix in a stem of the poppet valve.
 18. A method of reducing contact area of a valve in an engine to reduce valve seat load, to reduce valve spring load, to increase air-fuel mixture under a seat of the valve, and to reduce lifter and camshaft load, the method comprising: reducing a mass of a valve by forming a helical portion about a stem of the valve; installing the valve in a cylinder head of an engine; and increasing engine efficiency by reducing a coefficient of drag of the valve, wherein the helical portion is configured to have reduced surface contact in the engine.
 19. The method as in claim 18, wherein the helical portion has more than one start.
 20. The method as in claim 18, wherein the mass removed is between about twenty percent to about twenty-five percent of a diameter of the stem. 